(a) Field of the Invention
This invention, in its broadest aspect, relates to enzyme inhibitors. In particular, it relates to compounds of Formula I which are useful in preventing or treating disease states caused by the action of proteases and other enzymes on mammalian elastin or other proteins. More particularly, the invention relates to certain novel compounds useful in preventing or treating disease states caused by the degradative action of elastases or cathepsin G. In another aspect, it relates to novel intermediates of Formula II for preparing compounds of Formula I.
Elastin is the functional protein component of elastic fiber tissues, a component of connective tissues. Elastic tissue is relatively rich in elastin and has a distinct rubber-like property. Most specifically, the ligamentum nuchae and the vocal cords, the vertebral ligamenta flava, the aorta, and the pulmonary arteries of some mammals are considered elastic tissues. Elastic cartilaginous tissues such as those present in the ear and epiglottis are a specialized form of elastic tissue. Lung, bronchi and skin also contain elastin and are considered elastic tissue. Sandberg, et al., New England Journal of Medicine, Mar. 5, 1981, 566-579.
Elastase is an elastinolytic enzyme which causes degradation and fragmentation of elastic fibers by its catalytic activity against elastin. Elastases originate from a number of sources and can be found in microorganisms, snake venoms and a number of mammalian cells and tissues including pancreas, polymorphonuclear leukocytes, and macrophages. In a normally functioning mammal, elastase is required for turnover of damaged cells and the digestion of certain invading bacteria. This invention in particular relates to the class of elastases known as the Serine Proteases.
Excessive elastin degradation has been associated with pulmonary emphysema, adult respiratory-distress syndrome, arthritis, atherosclerosis, certain skin diseases, and certain inflammatory processes leading to localized protein breakdown. Werb, et al., Journal of Investigative Dermatology, 79: 154S-159S, (1982); Rinaldo, et al., New England Journal of Medicine, 306: 900-909, (1982). By inhibiting elastase therefore it is possible to mediate, eliminate or treat a wide variey of disease conditions.
A number of inhibitors of elastase are known. Peptide chloromethyl ketones have been shown to be irreversible inhibitors of elastase. But difficulties must be considered when the in vivo use of peptide chloromethyl ketones is contemplated. The compounds are electrophiles and can react with good nucleophiles such as the thiol groups of glutathione and various proteins. During any long term treatment with these inhibitors, such non-specific alkylation could lead to the introduction of new antigenetic determinants and an autoimmune response and/or could behave similarly to the known nitrogen mustards, etc. Peptides containing aza-amino acid residues (aza peptides) are another class of inhibitors. The effectiveness of aza-peptides as elastase inhibitors depends on the rate of acylation, which in most cases is instantaneous, and also on the rate of deacylation. As such, these compounds while useful tools in studying the in vitro properties of elastase are still largely unsuitable for in vivo use.
(b) Information Disclosure
The treatment of certain disease states by inhibitors of elastase is known as described above.